On 05/04/2011 09:59 PM, shaohua.li@intel.com wrote:

flush request isn't queueable in some drives. Add a flag to let driver
notify block layer about this. We can optimize flush performance with the
knowledge.

Signed-off-by: Shaohua Li<redacted>
---
  block/blk-settings.c   |    6 ++++++
  include/linux/blkdev.h |    7 +++++++
  2 files changed, 13 insertions(+)

hmmm.

This assumes that flush on new hardware, by default, is queueable.

I think the sense should be reversed:  don't enable the optimization, 
unless we know the optimization works.

That seems safer than always enabling the optimization, unless we know 
it does not work.  That is not a fail-safe mode of operation.

	Jeff